Modern construction equipment contains multiple components that are actuated to move. For example, a crane might include a rotating bed having a boom, the boom might pivot vertically and extend longitudinally, and at least one outrigger may extend from the cab horizontally and engage the ground vertically. Each of these components is typically controlled by an operator during use of the equipment.
In recent years safety concerns have become paramount in the industry. For example, recent crane regulations require the use of Outrigger Monitoring Systems (OMS). Such a system may be used to measure the length of an outrigger to determine crane stability. Traditionally, the measurement of extension of an outrigger has been done using various physical sensors such as string potentiometers, magnetic sensors, and limit switches. These different sensors each have limitations that limit their use. String potentiometers, while potentially having acceptable measurement resolution, are susceptible to breakage and infiltration by particulates. Magnetic sensors are generally durable, but generally do not have the resolution required. Limit switches are subject to mechanical failure and are only able to measure discrete distances.
An optical measurement system has been proposed for measuring lengths, but it has its own drawbacks as well. For example, while an optical measurement system is potentially very accurate and not susceptible to mechanical failure, it is susceptible to dirt obscuring the sensor or airborne particulates disrupting the beam. For these reasons, optical measurement systems have been unsuccessful for extended use in construction equipment.
It would be beneficial to have a system and method for measuring a linear distance in a harsh environment that has the advantages of being accurate, not susceptible to mechanical wear, and not susceptible to interference from debris.